Remote Sensing-based Yield Curves (RSYC) for Canada’s Forested Ecozones

authors

NRCan-CFS-logo

Yield curves & growth simulators

  • function of age & species
  • project forest attributes into the future

Carbon accounting

CBM-CFS3 architecture

https://natural-resources.canada.ca/climate-change/climate-change-impacts-forests/carbon-accounting/13087

National Forest Carbon Monitoring, Accounting and Reporting System (NFCMARS) is designed to:

  • estimate past changes in forest carbon stocks, such as from 1990 to the present (monitoring)

  • predict changes in carbon stocks, based on scenarios of future disturbance rates and management actions, in the next 2 to 3 decades (projection)

Existing models - limitations

  • spatial extent (single jurisdiction, Canada-wide)

  • developed for the dominant (most common) species only

  • developed for managed forests

  • often based on a limited number of samples

Aim: Remote Sensing-based Yield Curves (RSYC)

  • Entire Canada (all treed pixels)

  • Species-specific (not only most common tree species)

  • Consistent methodology

  • Locally representative

  • Fine level of spatial detail

  • Designed to work with RS data

Data

Tiling

Approach

  1. Build a chronosequence of AGB by combining multiple pixel-level AGB time series
  2. Develop a filtering approach to screen Landsat-derived AGB
  3. Fit non-linear mixed effects models (NLME)

Approach

Modeling

Model form after (Fortin and Lavoie 2022):

\[ AGB = \beta_1 e^{-\beta_4 age} (1 - e^{-\beta_2 age})^{\beta_3} \]

NLME:

  • nested tile/pixel random effect
  • random parameter: \(\beta_1\)

Results

National AGB yield curves (N=1892)

Multi-species:

  • Generic (all species) – 389
  • Coniferous – 355
  • Broadleaf – 184

Species-specific:

  • 27 species-specific models (some for a single tile only, up to 308 for black spruce)

Model evaluation

  • Yield curves represent the average AGB in the tile

  • Evaluation – compare mean AGBRSYC with AGBREF by 20 year age classes

Model evaluation

MAGPlot data:

  • Over 50k plots, harmonized dataset

  • Independent

  • Mix of different sampling designs

  • Raking ratio: weights (per plot) to adjust for under- or over-representation of different forest strata (e.g. plots located in more productive stands)

Next steps

  • Uncertainty (confidence intervals)
  • Different spatial units (ecodistricts, ecoregions)
  • Volume instead of AGB
  • Ensemble models (multiple AGB inputs)

Questions?


Publications (open access):

Tompalski, P., Hermosilla, T., Baral, S.K., Wulder, M.A., White, J.C. 2025. National remote sensing-derived aboveground biomass yield curves for Canada. Forestry: An International Journal Of Forest Research. https://doi.org/10.1093/forestry/cpaf067

Tompalski, P., Wulder, M.A., White, J.C., Hermosilla, T., Riofrío, J., Kurz, W.A., 2024. Developing aboveground biomass yield curves for dominant boreal tree species from time series remote sensing data. Forest Ecology and Management 561, 121894. https://doi.org/10.1016/j.foreco.2024.121894

R package: https://ptompalski.github.io/RSYC

This presentation: https://ptompalski.github.io/RSYC_overview/

References

Fortin, Mathieu, and Jean-François Lavoie. 2022. “Reconciling Individual-Based Forest Growth Models with Landscape-Level Studies Through a Meta-Modelling Approach.” Canadian Journal of Forest Research, April. https://doi.org/10.1139/cjfr-2022-0002.
Hermosilla, Txomin, Alex Bastyr, Nicholas C Coops, Joanne C White, and Michael A Wulder. 2022. “Mapping the Presence and Distribution of Tree Species in Canada’s Forested Ecosystems.” Remote Sensing of Environment 282 (December): 113276. https://doi.org/10.1016/j.rse.2022.113276.
Maltman, James C., Txomin Hermosilla, Michael A. Wulder, Nicholas C. Coops, and Joanne C. White. 2023. “Estimating and Mapping Forest Age Across Canada’s Forested Ecosystems.” Remote Sensing of Environment 290 (May): 113529. https://doi.org/10.1016/j.rse.2023.113529.
Matasci, Giona, Txomin Hermosilla, Michael A. Wulder, Joanne C. White, Nicholas C. Coops, Geordie W. Hobart, and Harold S. J. Zald. 2018. “Large-Area Mapping of Canadian Boreal Forest Cover, Height, Biomass and Other Structural Attributes Using Landsat Composites and Lidar Plots.” Remote Sensing of Environment 209 (May): 90–106. https://doi.org/10.1016/j.rse.2017.12.020.